RE: IML: 1983 Imperial: EFI - Starts but will not idle after warm up

["Dick Benjamin" <dickb@xxxxxxxxx>]

Bill, I don't recall this exact symptom, but I can give you a list of things
to check.  These are in the order of "cheap and easy" to "tough and time
consuming":

First, pull the connector off the EFI coolant sensor (the one with two
prongs that is screwed into the water jacket of the intake manifold next to
the upper radiator hose outlet.  You should measure the resistance between
the two terminals when the engine is cold, and again when it is warm.  The
correct measurements are around 900 ohms at room temp, and much higher (1500
ohms or so) at 180F.  Don't remove the sensor unless you are certain it is
bad AND you have a replacement handy, they often crumble when you try to
take them out!  These numbers are not critical; anything within 30% or so is
fine.

Next, just replace the O2 sensor - they're cheap, and easy to change.  It is
out of the circuit while the car is warming up, so a failure wouldn't show
up until after the warm-up period.

If you're still not OK, do the setup for running the engine with the cover
off the air cleaner - it should start fine, and sit there and idle without a
problem even when it is warmed up.  It won't drive very well, because you
will have no air flow sensor operating, but you can check for any fuel
nozzle problems by inspecting the streams of fuel from the nozzles - there
should be no leakage from the plumbing, and no stray squirts anywhere.

If that produces no improvement, I think there may be a problem with the EGR
valve - try disconnecting and blocking off the vacuum line that operates it,
then put another line on the valve.  Apply vacuum to it to see if you can
make it stall the engine at idle.  If you can make it operate that way, it
is probably all right.  These do carbon up and become stuck sooner or later
- the only cure is to replace the valve and clean out the passages in the
intake manifold.  Since your problem came on suddenly, the problem may be in
the control system for the valve, so try driving the car with it
disconnected (line blocked off) to see if that clears the problem. 

If you still haven't found the problem, and you have a spare fuel flow
sensor, I'd try just swapping them. If you don't have one, you can squirt
some fuel injector cleaner into the fuel inlet line at the HSA and then
crank the engine briefly to suck the cleaner into the fuel inlet plumbing
and fuel flow sensor.  After all these years, the various dies used to color
different brands of gasoline can contaminate the optical sensor in the fuel
flow sensor.  After you think you have gotten a few ounces of the cleaner
into the HSA, just let it sit for a while and do its thing - then hook up
the fuel line and see if there is any improvement.

If there is still no improvement, we'll have to go to plan B.  Right now, I
don't know what plan B is, though.  We might have to check the windshield
washer bottle.

Dick Benjamin

-----Original Message-----
From: mailing-list-owner@xxxxxxxxxxxxxxxx
[mailto:mailing-list-owner@xxxxxxxxxxxxxxxx] On Behalf Of Bill Watson
Sent: Friday, April 14, 2006 11:13 PM
To: mailing-list@xxxxxxxxxxxxxxxx
Subject: IML: 1983 Imperial: EFI - Starts but will not idle after warm up


After running great for the past two years, my 1983 Imperial with EFI has
decided not to run after warmed up.  It will start and idle smoothly while
warming up.  It will even drive smoothly while warming up.

But once it is warmed up (the EFI equivalent of the choke cutting out) it
becames very balky.  It will surge at times, momentarily die out and have
absolutely no power, unless you are going downhill.  Going up uphill you
just cross your fingers and hope it will make it before it dies.  When
parked, it will do the same and eventually just die.  Giving it gas while at
a standstill will keep it going with everything at a slightly higher rpm.
But was soon it returns to normal idle, it will die.

I have an idea someone had this problem sometime in the past, but I cannot
find anything on it.

Any ideas?

Bill
Vancouver, BC



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